A rumor has been going around for about four months now that Valve is coming out with a Linux version of Steam and had a lot of people in the Linux community very excited. However Valve have officially killed the rumor. And it is not what people wants to hear - there is no Linux version of Steam in development.

wow... two things here... first, Steam != source engine.
Second, the thing here is probably more about products to be delivered through steam than the technical difficult of porting it.

Soon as more games are officially ported and distributed to linux, it will be viable to Steam to support a native steam client to linux... and "more games" probably means many more than source-engine games, I mean, third party ones! ;]